The LEICA SUMMILUX-M 21mm f/1.4 ASPH extends Leica's series of high speed M lenses into the wide-angle range.
It offers excellent performance over the entire image field even at full stop and in the close-up range thanks to a "floating ele-
ment". Stopping down to 2.8 leads to an absolutely outstanding image quality, in fact, in comparison to the Elmarit lens of the
same focal length, its rendition is slightly more uniform across the image field.
The vignetting typical of every optical system is
naturally more apparent with a super wide angle lens, particularly a high speed one like this, than on standard lenses or those
with a long focal length. At full stop with the 35mm format, its maximum - i.e. in the corners of the image - is around 3.2 aperture
stops or, with the Leica M8 models and their slightly smaller format, around 1.9 aperture stops. Stopping down to 2.8 visibly
reduces this light fall-off towards the image edges to 1.7 or 0.8 aperture stops. Stopping down further does not bring any noticea-
ble additional reduction, as all that remains is essentially the natural vignetting. The maximum distortion of the lens is 2.3%,
which in practical terms is negligible for the majority of photographic applications.
A total of ten lens elements are used to achie-
ve this exceptional performance. To correct color aberrations, five of these are made of glass types with anomalous color disper-
sion (partial dispersion), while a further two have aspherical surfaces. To maintain performance in the close-up range, one group
towards the rear of the optical system is a "floating element" that moves independently of the rest of the mechanism.
Summary: The LEICA SUMMILUX-M 21mm f/1.4 ASPH offers maximum image performance with a focal length / speed combina-
tion previously unavailable in the M system. This extends the composition options of M photography, particularly for available light
shots, but also thanks to a previously unattainable reduction in the depth of field in combination with large angles of view. |
